update list enclosed in tuple

Question

Basically I want to achieve a tuple (or any datatype that fits my problem) that contains a list that can be updated. Because of immutability and such the below demonstrator code does not work of course. It is only to illustrate better what I want to achieve.

I wonder of there are any elegant ways, datatypes (IOREfs?) or modules that would do that for me or if in such a case I really would need to take apart the whole tuple, and reconstruct it with the updated elements.

By the way: intuitively I would have expected that at least as long as test is not printed the list msgs will not be evaluated.

test = ("192.168.1.1", 3455, (1234566, msgs))
msgs = ["aaa", "bbbb", "ccccc"]

main = do
     --print test
     let msg_tmp = "first" : msgs
     let msgs = msg_tmp
     print msgs
     print test 

Answer 1

As others have stated, there should be very specific and weighty reasons for not doing things the functional way. Your tuple seems needlessly convoluted, but you could go about creating a new one with the extra message like this:

addMsg (a,b,(c,msgs)) msg = (a,b,(c,msg:msgs))